Checksum

inCkSum

Calculates a 16-bit 1's complement checksum over the buffer *buf (of length len) and the msg *m, returning the bit complement of the sum. len should be even and the buffer must be aligned on a 16-bit boundary. len may be zero.

u_short inCkSum (Msg * m, u_short * buf, int len);

ocsum

Returns the 1's complement sum of the count 16-bit words pointed to by hdr, which must be aligned on a 16-bit boundary.

u_short ocsum ( u_short * hdr, int count);